As for a kind of power semiconductor devices, a JBS (Junction Barrier Schottky) diode having a Schottky diode and a pn diode in parallel or an MPS (Merged-PiN Schottky) diode is known (referred to as a JBS diode, below).
As for a JBS diode using a silicon semiconductor, a semiconductor device has been known whose p-type region includes a low impurity density portion (P−) and a high impurity density portion (P+) covering a top portion thereof (for example, Patent Document 1). Patent Document 1 describes that a JBS diode having less minority carrier accumulation in a pn diode portion and a short reverse recovery time can be obtained.
Furthermore, as for a JBS diode using a silicon carbide semiconductor, a configuration has been known in which an insulation region is provided between a Schottky diode portion and a pn diode portion (for example, Patent Document 2). Patent Document 2 describes that in a JBS diode using a silicon carbide semiconductor in which an insulation region is not provided, a pn diode does not conduct electricity in the on-state.